Truck cab space frame

ABSTRACT

A space frame for a truck cab, the space frame having a pair of hydroformed, longitudinally extending inner side rail members, a laterally extending and hydroformed connecting member extending between the inner side rail members and extending laterally beyond each of the inner side rail members. The connecting member being constructed and arranged to hold the pair of inner side rail members in laterally spaced relation to one another. The space frame also having a U-shaped and hydroformed first upper cross member having a pair of leg portions forming rear pillar structures and a transverse bight portion. Each of the rear pillar structures being connected to and extending upwardly from the connecting member, and the pair of inner side rail members being positioned between and spaced from the pair of leg portions.

[0001] This application claims the benefit of U.S. ProvisionalApplication Ser. No. 60/326,211, filed on Oct. 2, 2001, the entirecontents of which are hereby incorporated herein by reference thereto.

FIELD OF THE INVENTION

[0002] The present invention is generally related to motor vehicleframes and more particularly to motor vehicle space frames constructedusing hydroformed members.

BACKGROUND OF THE INVENTION

[0003] The cab assembly for a truck is a box-like structure thatprovides an enclosed driver compartment at the front of the truck for adriver. Truck cabs are generally mounted on the truck frame. The cabassembly can include a pair of windowed side doors, a front windshield,seats for the driver and a passenger, an instrument panel, and vehiclecontrols.

[0004] The front end of the cab assembly is pivotally mounted on theframe so the cab assembly can move between an operative position and anopen position with respect to the frame. In its operative position, thecab assembly is releasably latched to the frame. The rearward end of theunlatched cab assembly can be pivoted generally upwardly and forwardlyaway from the frame to the open cab assembly position to allow access tothe engine and related components. Truck cabs are most commonlyconstructed of stamped and/or roll formed parts that are weldedtogether.

[0005] Examples of prior art truck cabs can be found in U.S. Pat. No.6,260,912 to Mondragon Sarmiento; U.S. Pat. No. 4,978,163 to Savio, andU.S. Pat. No. 3,055,699 to May, the entire disclosures of which areincorporated herein by reference thereto.

SUMMARY OF THE ILLUSTRATED EMBODIMENT OF THE INVENTION

[0006] The illustrated embodiment provides a space frame for a truckcab, the space frame comprising a pair of hydroformed, longitudinallyextending inner side rail members; a laterally extending and hydroformedconnecting member extending between the inner side rail members andextending laterally beyond each of the inner side rail members, theconnecting member being constructed and arranged to hold the pair ofinner side rail members in laterally spaced relation to one another; anda U-shaped and hydroformed first upper cross member having a pair of legportions forming rear pillar structures and a transverse bight portion,each of the rear pillar structures being connected to and extendingupwardly from the connecting member, and the pair of inner side railmembers being positioned between and spaced from the pair of legportions.

[0007] The illustrated embodiment further provides space frame for amotor vehicle, comprising a main frame assembly; and a cab assemblypivotally coupled to the main frame assembly, the cab assembly having apair of hydroformed, longitudinally extending inner side rail members; alaterally extending and hydroformed connecting member extending betweenthe inner side rail members and extending laterally beyond each of theinner side rail members, the connecting member being constructed andarranged to hold the pair of inner side rail members in laterally spacedrelation to one another; and a U-shaped and hydroformed first uppercross member having a pair of leg portions forming rear pillarstructures and a transverse bight portion, each of the rear pillarstructures being connected to and extending upwardly from the connectingmember, and the pair of inner side rail members being positioned betweenand spaced from the pair of leg portions.

[0008] The illustrated embodiment further provides a method of forming aspace frame for a cab, comprising forming each of the pair ofhydroformed, longitudinally extending inner side rails, hydroformedconnecting member, and first upper cross member by a method comprising,providing a tubular metallic blank having a tubular metallic wall;placing the tubular metallic blank into a die cavity of a die assembly,the die cavity having die surfaces, and providing a high pressure fluidinto an interior of the blank to expand the metallic wall of the centralportion of the blank outwardly into conformity with the surfaces of thedie cavity to define the respective hydroformed member; mounting theconnecting member to each of the inner side rails; and mounting thefirst upper cross member to the connecting member.

[0009] Other aspects, features, and advantages of the present inventionwill become apparent from the following detailed description of theillustrated embodiment, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a perspective view of a space frame for a cab assemblyconstructed according to the principles of one embodiment of the presentinvention for a truck and showing a plurality of body panels of the cabassembly secured to the space frame;

[0011]FIG. 2 is a perspective view of a lower frame assembly of thespace frame of FIG. 1;

[0012]FIG. 3 is a perspective view of the lower frame assembly with afloor structure and portions of a pair of forward pillar assembliesmounted thereon of the space frame of FIG. 1;

[0013]FIG. 4 shows the lower frame assembly of FIG. 3 with an upperportion of the space frame, including the assembled forward pillarassemblies, mounted thereon and showing an upper support structuremounted thereon;

[0014]FIG. 5 is a cross sectional view of a pair of space frame jointstaken through the line 5-5 of FIG. 4;

[0015]FIG. 6 is a cross sectional view of a rear attachment bracketassembly taken through the line 6-6 of FIG. 2;

[0016]FIG. 7 is a cross sectional view taken through the line 7-7 asindicated in FIG. 4;

[0017]FIG. 8 is an exploded view showing a forward pillar assembly ofthe space frame of the cab assembly of FIG. 1 and showing fragmentaryportions of a pair of hydroformed members of the space frame of FIG. 1;

[0018]FIG. 9 is a schematic side elevational view showing a truck thatincludes the cab assembly of FIG. 1 and showing of a portion of atrailer attached to the truck;

[0019]FIG. 10 is a view similar to FIG. 9 except showing the cabassembly in an open position;

[0020]FIG. 11 is a schematic view of a tubular hydroforming die assemblyshowing a blank mounted therein for forming an outer side rail member ofthe space frame of FIGS. 1-4;

[0021]FIG. 12 is a view similar to FIG. 11 except showing thehydroformed outer side rail member within the die cavity;

[0022]FIG. 13 is a view similar to FIG. 12 except showing anotherhydroformed outer side rail member in the die cavity that has a longerrearward portion than the hydroformed member shown in FIG. 12; and

[0023]FIG. 14 is another embodiment of the cab assembly.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT OF THE INVENTION

[0024]FIGS. 1-4 illustrate various stages of the construction of anexample cab assembly 10 (FIG. 1) constructed according to one embodimentof the present invention. The illustrated embodiment is preferably for atrailer-towing truck. The cab assembly 10 generally includes a spaceframe 12 and a plurality of body panel structures mounted on the spaceframe 12. The construction of the cab assembly 10 is illustrated inFIGS. 1-8. A schematic representation of an assembled truck 14 thatincludes an assembled cab assembly 10 is shown in FIGS. 9 and 10. Thecab assembly 10 provides a cab portion of the truck 14.

[0025] The example space frame 12 of the cab assembly 10 is primarily ofhydroformed construction, but some non-hydroformed components may alsobe incorporated in the space frame 12. As discussed below, other spaceframe embodiments constructed according to the principles of theinvention may be entirely of hydroformed construction.

[0026] The use of tubular hydroforming in the illustrated embodimentenables, for example, increased control frame stiffness, dimensionalaccuracy, fatigue life, and vehicle crashworthiness while reducing framemass and cost (relative to frames constructed using conventional,non-hydroformed techniques).

[0027] Tubular hydroforming is a metal-forming process which may use,for example, a high-pressure fluid to outwardly expand a tubular metalblank into conformity with the surfaces of a die cavity of a dieassembly to form an irregularly shaped tubular part. Because the shapeof the die cavity determines the shape of the part, tubular hydroformedmembers may therefore be provided with a wide range of geometries incomparison with other methods of forming parts. Each tubular hydroformedframe member may be formed to have a cross-sectional configuration thatvaries continuously along its length, to the configuration desired andeach frame member may be formed to curve or “bend” along its length todefine different portions of a vehicle frame such as frame side railsand frame pillars in a single tubular hydroformed part.

[0028] Forming the parts by hydroforming provides the opportunity toreplace several stamped parts of existing stamped frames with singlehydroformed parts. When this is accomplished in a vehicle frame that hasbeen heretofore of stamped construction, for example, an existingvehicle frame design could be made lighter, stronger and at a reducedcost because, for example, fewer parts would be required to constructthe frame, fewer machines would be required during manufacturing, fewerwelds would be required, less material would be used, and so on.

[0029] The example space frame 12 of the cab assembly 10 is primarily ofhydroformed construction, but some non-hydroformed components are alsoincorporated in the space frame 12. As discussed below, other spaceframe embodiments constructed according to the principles of theinvention may be entirely of hydroformed construction.

[0030] As seen in FIG. 9, the truck 14 includes a truck frame assembly18 and a plurality of wheels 20 mounted on the frame assembly 18 bysuspension assemblies (not shown). The wheels 20 rollingly support theframe assembly 18 and include a set of driveable rear wheels 22 and aset of steerable front wheels 24. An engine assembly 26 (shownschematically in FIG. 10) is mounted on the frame assembly 18 and isoperatively connected to the rear wheels 22 for powered movement of thesame to move the truck 14. A steering assembly (not shown) is mounted ina cab portion of the cab assembly 10 and is operatively connected to thefront wheels 24 to steer the moving truck 14. The cab assembly 10 ismounted on the frame assembly 18 for movement between an operativeposition (see FIG. 9) in which the cab assembly 10 is releasably latchedto the frame assembly 18 and a raised position (see FIG. 10) in whichthe cab assembly 10 is unlatched from the frame assembly 18 and movedupwardly with respect thereto to provide access to the engine assembly26.

[0031] Space frames for any size cab assembly may be constructedutilizing the principles of space frame construction taught by theexample space frame 12. For example, a space frame may be constructedaccording to the teachings of the invention to have sufficient length(longitudinally) to include a rear sleeper compartment or a space framemay be constructed according to the teachings of the invention to have alesser longitudinal length so that the cab assembly does not include asleeper compartment.

[0032] The space frame 12 incorporates a significant number of tubularhydroformed components which allows the vehicle manufacturer to realizethe benefits offered by tubular hydroforming technology (relative tostamped and welded frame construction or roll formed construction, forexample) such as reduction of frame weight, improved vehiclecrashworthiness, reduction in the number of frame parts required toconstruct the frame, reduction in the number of welds required join theparts to one another (and therefore in the total number of weldsrequired to assemble the space frame 12), reduction in the amount ofwaste generated during manufacturing of the individual frame components,and so on. The example space frame 12 may utilizes non-hydroformedcomponents (specifically, a pair of stamped sheet metal forward pillarassemblies) to facilitate construction of the space frame 12 asdescribed below. These and other aspects of the tubular hydroformedconstruction of the space frame 12 will become apparent as the spaceframe 12 is considered in detail. Hydroformed space frames are generallyknown as can be understood from commonly assigned U.S. Pat. No.6,092,865 to Jaekel et al., for example, which is incorporated herein byreference in its entirety.

[0033]FIG. 2 shows a lower frame assembly 30 of the space frame 12 inisolation. The lower frame assembly 30 includes a pair of longitudinallyextending, laterally spaced outer side rail members 32, 34 and a pair ofinner side rail members 42, 44 of tubular hydroformed construction.Because the outer side rail members 32, 34 are of mirror imageconstruction to one another and because the inner side rail members 42,44 are of mirror image construction to one another, only rail members 32and 42 will be discussed in detail, but the discussion applies equallyto rail members 34 and 44, respectively. Corresponding portions of railmembers 32 and 34 and of rail members 42 and 44 are labeled withidentical reference numbers to facilitate discussion, but it isunderstood that these corresponding portions are of mirror imageconstruction.

[0034] The example rail member 32 is of one-piece tubular hydroformedconstruction and includes a forward rail section 36, an upwardly angledintermediate rail section 38 and an essentially straight rearwardsection 40. The inner side rail members 42, 44 are of one-piece tubularhydroformed construction and are positioned generally between the outerside rail members 32, 34. Each inner side rail member 42, 44 includes aforward rail section 46, an upwardly angled intermediate section 48 andan essentially straight rearward rail section 50.

[0035] Each hydroformed member 32, 34, 42, 44 is preferably a tubularstructure having a closed cross-section along its length and opentubular ends. Each member 32, 34, 42, 44 are hydroformed to have acontinuously varying cross-section along its length, so that the exactshape of the cross section and the cross-sectional area of each membervaries along its length as shown, for example, in FIG. 2. A portion ofan upper wall of each outer side rail member 32, 34 is cut out (by lasercutting, for example, or by other appropriate method) and removed fromeach member in two locations to provide a pair of pillar-receivingopenings 70, 72 in each member 32, 34. The openings 70, 72 receivedlower end portions of the B and C pillars, respectively, as describedbelow.

[0036] A laterally extending connecting structure in the form of arearward tubular hydroformed member 52 is connected to a rearward endportion of each of the outer side rail members 32, 34 and each of theinner side rail members 42, 44 at joints 54, 55, 56, 57, respectively.The member 46 holds the pair of outer side rail members 32, 34 inlaterally spaced relation to one another and holds the inner side railmembers 42, 44 in laterally spaced relation to each other and to theouter side rail members 32, 34.

[0037] The construction of joint 54 can be understood from FIG. 5. Joint55 is of mirror image construction and consequently is not separatelydiscussed. Sections of the vertically extending sidewalls 76 (only oneof which is shown in FIG. 5) and a section of the top wall portion 78 ofthe rearward member 52 are cut out and removed to form a notch 80 in theend of member 52. The outer side rail member 32 is secured in the notch80 by welding (MIG welding, for example) or other appropriate fasteningmethod.

[0038] The construction of joint 56 can be understood from FIG. 6.Sections of the vertically extending sidewalls 82 (only one of which isshown in FIG. 6) and a section of the top wall 84 of the inner side railmember 42 are cut out and removed to form a notch 86 in the inner siderail member 42. The rearward member 52 is secured within the notch 86 bywelding or by other suitable method. The walls 76, 78 of the hydroformedmember 52 and the walls 82, 84 of the hydroformed member 42 may be cutusing a laser or by any other appropriate method.

[0039] Forward laterally extending connecting structure in the form of apair of mounting structures 58, 60 is connected between a forward endportion of each outer side rail member 32, 34 and the associated innerside rail member 42, 44, respectively. The example mounting structures58, 60 are constructed of a metal material and are secured to opposingside surfaces of the members 32, 42 and 34, 44, respectively, bywelding, for example, or by other suitable joining technique. Themounting structures 58, 60 provide support structure for brackets (notshown) that are used to pivotally mount the cab assembly 10 to the truckframe assembly 18, as seen in FIG. 10.

[0040] As seen in FIG. 2, a pair of floor support structures 62, 64 aremounted on the forward rail sections 46 of each inner side rail member42, 44. Each support structure 62, 64 may be a stamped sheet metalstructure that includes opposing vertical wall sections 66, 67 and aconnecting wall 69. A lower portion of the vertical wall sections 66, 67of each support structure 62, 64 is secured to a respective side surfaceof the associated inner side rail member 42, 44 by welding or otherappropriate method. Each wall section 66, 67 includes a flange 68, 70.Each flange 68, 70 provides an upwardly facing angled support surfacethat supports a forward end portion of a floor structure 72 (shown inFIG. 3, for example) of the cab assembly 10.

[0041] A pair of rear attachment bracket assemblies 74, 75 are connectedto rearward portions of the pair of inner side rail members 42, 44,respectively. FIG. 6 shows the construction of the rearward attachmentbracket assembly 74. The structure of bracket assembly 75 can beunderstood from the description of the bracket assembly 74. The rearwardattachment bracket assembly 74 includes a bracket attachment structure88, a mounting bracket 90, a support structure 92, and a latch engagingmember 94. The bracket attachment structure 88, the mounting bracket 90and the support structure 92 may be made from a metallic material ofsuitable strength and may be shaped by stamping. The inner side railmember 42 is shaped (by cutting or other appropriate method) to have anotch 91. The bracket attachment structure 88 is secured by welding orother appropriate method within the notch 91 of the inner side railmember 42. The attachment structure 88 provides a relatively wide(relative to the width of the inner side rail member 42) downwardlyfacing surface 98 to which the mounting bracket 90 is attached. Themounting bracket 90 includes a top wall 100 and a pair of downwardlyextending forward and rearward walls 102, 104. An upwardly facingsurface of the wall 100 is secured to the downwardly facing surface 98of the attachment structure 88 by welding or other appropriate method.

[0042] The latch engaging member 94 is secured by welding or otherappropriate method in openings 106, 108 formed in the wall portions 102,104, respectively, of the mounting bracket 90. The latch engaging member94 in the example bracket assembly 74 is an elongated cylindricalstructure made of a metallic material. The support structure 92 has anL-shaped cross-section that includes a vertically extending wall portion110 and a horizontally extending wall portion 112. The support structure92 is secured to the space frame by welding or other suitable method.Specifically, the wall portion 110 is secured to a wall portion 76 ofthe tubular hydroformed cross member 52. The wall portion 112 of thesupport structure 92 is secured to the attachment structure 88. A pairof flanges (only one is visible in FIG. 6) are secured to respectivevertically extending sides of the inner side rail member 42. The supportbracket 92 helps secure the bracket assembly 74 to the space framemembers 52, 42 and also covers the open tubular end of the inner siderail member 42.

[0043] As shown in FIGS. 1-6, a plurality of the cab assembly componentsare secured to the lower frame assembly 30 including floor panstructures and a pair of forward pillar assemblies. Each of these cabassembly components may be non-hydroformed. In the example cab assembly10, each of these components is constructed of stamped sheet metal.

[0044] As best seen in FIG. 3, the cab assembly 10 has a multi-piecefloor structure (although the floor structure could be of single-piececonstruction in some embodiments of the cab assembly) that includes acentral floor pan structure 142, a pair of side floor pan structures144, 146 and a laterally extending rear floor pan structure 148. Theside floor pan structures 144, 146 are secured to portions of the twopairs of side rail members 32, 42 and 34, 44, respectively. A forwardportion of each side floor pan structure 144, 146 is supported by thepair of support structures 62, 64 mounted on the rail members 42 and 44.

[0045] A rearward portion of the central floor pan structure 142 issecured to and supported by the inner side rail members 42, 44. Aforward portion of the central floor pan structure 142 is secured to thesupport structures 62, 64. The longitudinally extending side edgeportions of the central floor pan structure 142 are secured to adjacentlongitudinally extending side edge portions of the side floor panstructures 144, 146. The rear floor pan structure 148 extends laterallybetween the outer side rail members 32, 34 and is secured to rearwardportions of the outer side rail members 32, 34, to a forwardly facingside surface of the rearward member 52 and to portions of the inner siderail members 42, 44.

[0046] The forward rail sections 36, 46, the intermediate rail sections38, 48 and a forward portion of the rearward sections 40, 50 of theouter and inner side rail members 32, 34 and 42, 44, respectively,generally define the longitudinal extent of a cab portion 150 of the cabassembly. The rearward portion of each of the rearward sections 40, 50of the outer and inner side rail members generally define thelongitudinal extent of a rear compartment portion 152 of the cabassembly. As explained below, the rear compartment portion 152 of thecab assembly 10 can be constructed for use as a storage compartment orcan be constructed to be a sleeper compartment that includes one or morebeds.

[0047] A pair of forward pillar structures 154, 156 are mounted on alower frame assembly 30. The forward pillar structures of the examplespace frame include a pair of forward pillar assemblies 154, 156(partially shown in FIG. 3 and one of which, 154, is shown in crosssectional and exploded views in FIGS. 7 and 8, respectively, forexample). The forward pillar assemblies 154, 156 are of mirror imageconstruction to one another in the example space frame 12 and can be ofstamped sheet metal construction. Because of the mirror imageconstruction, only assembly 154 is considered in detail. Each forwardpillar assembly 154, 156 is connected to a respective outer side railmember 32, 34 and extends upwardly therefrom. As explained below, eachforward pillar assembly 154, 156 provides a lower portion of theforwardmost or A pillar on each side of the space frame 12.

[0048] The construction of the forward pillar assembly 154 and themanner in which the components of the pillar assembly 154 and the outerside rail member 34 are connected to one another can be understood from,for example, FIGS. 3, 4, 7 and 8. The forward pillar assembly 154includes an outer pillar member 158 and an inner pillar member 160. FIG.8 shows a fragmentary portion of the forward rail section 36 of theouter side rail member 34, the inner and outer pillar members 158, 160,and a fragmentary portion of an upper longitudinal member 162 (describedbelow) of the space frame 12 in exploded relation with one another. Theinner and outer pillar members 158, 160 may be stamped sheet metalstructures that are secured to one another and to the tubularhydroformed outer side rail member 32 by welding, or by any appropriatemethod.

[0049] A lower portion 164 of the inner pillar member 160 is secured tothe outer side rail member 32 by welding or other appropriate method. Alower portion 168 of the outer pillar member 158 is secured to the outerside rail member 32. Upper portions of the outer and inner pillarmembers 158, 160 are secured to one another in the assembled space frame12. A forward end portion of the upper longitudinal member 162 issecured between the outer and inner pillar members 158, 160 in theassembled space frame 12.

[0050] The upper longitudinal member 162 may be secured to the innerpillar member 160 before the outer pillar member 158 is secured to theinner pillar member 160 and the upper longitudinal member 162 or,alternatively, the space frame may be assembled by securing the outerand inner pillar members 158, 160 to one another and then securing thefree end of the upper longitudinal member 162 therebetween.

[0051] Each forward pillar assembly 154, 156 has a closed, tube-likecross section (see FIG. 7, for example). The inner and the outer pillarmembers 160, 158 each include an outwardly extending wall portion 169,171, respectively, that are secured to one another (by welding, forexample) in overlapping, abutting engagement Wall portions 173, 175 ofthe inner and outer pillar members 160, 158, respectively, are securedto one another (by welding, for example) in overlapping, abuttingengagement. The tubular construction of the forward pillar assemblies154, 156 provides the A pillars with a high degree of strength. Theouter pillar member 158 includes a recess 177 shaped to receive aperipheral portion of a vehicle door (not shown). The recess 177includes an outwardly facing wall surface 179 constructed and arrangedto engage a door seal (not shown) to seal the closed vehicle door.

[0052] The forward pillar assemblies 154, 156 and a plurality of uppertubular hydroformed members comprise an upper frame assembly 181 that ismounted on the lower frame assembly 30 to provide the upper portion ofthe space frame 12. The upper tubular hydroformed members include thepair of upper longitudinal members 162, 163, a tubular hydroformedU-shaped intermediate member 170 and a tubular hydroformed U-shaped rearmember 172. The assembled upper frame assembly 181 forms a cage-likestructure that supports a plurality of body panels in the assembled cabassembly 10.

[0053] As seen in FIG. 4, the intermediate member 170 is an invertedU-shaped hydroformed cross member having a central bight portion 174 anda pair of leg portions 176, 177 extending downwardly from junctures 178,179 at respective opposite ends of the bight portion 174. The rear crossmember 172 is another inverted U-shaped hydroformed cross member havinga central bight portion 180 and a pair of leg portions 182, 183extending downwardly from junctures 184, 185 at respective opposite endsof the bight portion 180.

[0054] A free end of each leg portion 176, 177 of the intermediate crossmember 170 is connected (at joints 196, 197) to a respective outer siderail member 32, 34 to form one of a pair of intermediate pillarstructures (which are the B pillars in the example space frame 12). Thebight portion 174 of the intermediate cross member 170 providesattachment and support structure for a roof (not shown) of the assembledcab assembly 10.

[0055] A free end of each leg portion 182, 183 of the rear cross member172 is connected (at joints 198, 199) to a respective outer side railmember 32, 34 to form one of a pair of rear pillar structures (which arethe C pillars in the example space frame 12). The bight portion 180 ofthe rear cross member 172 provides attachment and support structure fora roof (not shown) of the assembled cab assembly 10.

[0056] The joints 196, 197, 198, 199 are of similar construction and canbe understood from the discussion of joint 198. Joint 198 is shown incross section in FIG. 5. The opening 72 in the outer side rail member 32is sized to receive a free end portion of the leg 182 of the crossmember 172. When the leg 182 is placed through the opening 72, opposingouter surfaces of the wall portions 201, 202 of the leg 182 are inabutting engagement with inner surfaces of opposing, generallyvertically extending wall portions 203, 205 of the outer side railmember 32. The leg portion 182 and the outer side rail member 32 may besecured together by, for example, welding (MIG welding, single side spotwelding, and so on) or by any other suitable method.

[0057] As seen in FIG. 4, the upper longitudinal members 162, 163 are ofmirror image construction in the example space frame 12. Therefore, onlyupper longitudinal member 162 is considered in detail. Correspondingportions of the two upper longitudinal members 162, 163 are designatedwith identical reference numbers for convenience of discussion.

[0058] The upper longitudinal member 162 includes a longitudinallyextending rail-forming portion 192 and a pillar-forming portion 194.Generally, the rail-forming portion 192 of the upper longitudinal member162 is secured in overlying relation to the cross members 170, 172 atjoints 195, 197 and the free end of the pillar-forming portion 194 issecured to an upper portion of the forward pillar assembly 154. Thepillar-forming portion 194 of the upper longitudinal member 162 and theassociated forward pillar assembly 154 form an A pillar of the examplespace frame 12.

[0059] In the example space frame, the juncture 178 of the intermediatecross member 170 is welded or otherwise attached in surface-to-surfacerelation to an intermediate portion of the rail portion 192 of arespective upper longitudinal member 162. Similarly, the juncture 184 ofthe rear cross member 172 is welded or otherwise attached insurface-to-surface relation to a rearward portion of the rail-formingportion 192 of the upper longitudinal member 162. The rail-formingportion 192 is thus coupled to an upper portion of an associated rearpillar structure and extends forwardly therefrom to define a roofsupport rail that supports a portion of the roof of the assembled cabassembly 10.

[0060] A plurality of panels are mounted on the upper frame assembly 181(see FIGS. 1 and 4, for example). An upper support assembly 199 ismounted between the upper longitudinal members 162, 163 generally in thearea of the junctures between the rail-forming portions 192 and thepillar-forming portions 194 thereof. The upper support assembly 199 maybe of multi-piece stamped sheet metal construction (as shown in theexample space frame 12) and may be assembled and secured between theupper longitudinal members 162, 163 by welding or other appropriatemethod.

[0061] As seen in FIG. 1, a pair of lower front support structures 200,202 are mounted between the forward pillar assemblies 154, 156. Thelower front support structures 200, 202 may be of stamped sheet metalconstruction and may be secured to the space frame 12 by welding orother appropriate method. The lower front support structures 200, 202support a lower edge of a front windshield (not shown) of the cabassembly 10 and provide support structure for a vehicle instrument (ordash) panel (not shown) of the assembled cab assembly 10. The lowerfront support structure 200 includes a plurality of openings 203, whichcan be for mounting such items as vehicle headlights.

[0062] An upper front support structure 204 is mounted on the upperfront support assembly 199. The upper front support structure 204 may beof stamped sheet metal construction (as shown in the example space frame12) and may be of single- or multi-piece construction (it is multi-piecein the example space frame 12). The upper front support structure 204may be secured to the upper front support assembly 199 by welding orother appropriate method. The upper front support structure 204 and theupper front support assembly 199 provide support for a forward portionof the roof (not shown) of the cab assembly 10 and for an upper portionof the vehicle windshield.

[0063] A pair of side structures 206, 208 (of mirror image constructionto one another in the example space frame 12) are mounted to the B and Cpillar pairs 176, 182 and 177, 183, respectively, and to the railportions 40, 192 on each side of the space frame 12. The side structures206, 208 may be of stamped sheet metal construction (as shown in theexample space frame 12) and may be secured to the space frame 12 bywelding or other appropriate method.

[0064] A pair of upper rear support structures 210, 212 and a pair oflower rear support structures 214, 216 are mounted in the rear of thespace frame 12. The structures 210, 212, 214, 216 may be of stampedsheet metal construction and may be secured to the space frame 12 bywelding or other appropriate method. The upper rear structures 210, 212are secured to the leg portions 182, 183 and to the cross portion 180 ofthe rear U-shaped member 172. The lower rear structures 214, 216 aresecured to the cross member 52 and to the lower portions of the legportions 182, 183 of the U-shaped member 172. The upper and lower rearstructures 210, 212, 214, 216 are secured together along seam 218.

[0065] A pair of door seal interface structures 217, 219 are mounted onthe door opening 221 on each side of the cab assembly 10. Each door sealinterface structure 217, 219 may be of stamped sheet metal constructionand may be secured to the space frame 12 in the vicinity of joints 196and 195, respectively, to provide an arcuate transition surface toengage a door seal (not shown) to seal an associated vehicle door (notshown) when the door is closed.

Hydroforming Method

[0066] Because many of the structural features of each hydroformedmember are formed during a hydroforming operation that creates the same,a preferred method of hydroforming the tubular hydroformed components ofthe space frame 12 will be considered. A hydroforming operation forforming a tubular hydroformed outer side rail member 32 can beunderstood from FIGS. 11 and 12. Each hydroformed member (such as ahydroformed U-shaped member 170 or 172, a hydroformed upper longitudinalmember 162, 163 or a hydroformed side rail member 32, 34, 42, 44) may beformed from an appropriately shaped tubular blank.

[0067] An example blank 220 for forming the outer side rail member 32 isshown in FIG. 11. The blank 220 is constructed of a suitable metallicmaterial and has a closed transverse cross section and open tubularends. The example blank 220 is constructed of a suitable grade of steel.Each blank 220 may be formed by any suitable method. For example, acontinuous strip of metallic material may be shaped by roll forming intoa tube and then seam welded to have a closed transverse cross section.Alternatively, a continuous length of metallic tubing may be formed byextrusion. The continuous tubular structure may then be cut to thelength required to form the blank 220.

[0068] The blank 220 is bent into an angular shape prior to being placedin a hydroforming die assembly. The blank 220 includes a forward portion222, an intermediate portion 224 and a rear portion 226. The blank 220may be bent in a computer numeric controlled (“CNC”) bending machineprior to being placed in the die assembly or, alternatively, may be bentby stretch bending to achieve the angular shape. If a relatively “sharp”angle (that is, at an angle greater than 30°) is to be formed in ablank, each sharp angle can be formed according the teachings of U.S.Pat. No. 5,953,945 entitled METHOD AND APPARATUS FOR WRINKLE-FREEHYDROFORMING OF ANGLED TUBULAR PARTS, which is hereby incorporatedherein by reference in its entirety. The teachings of the '945 patentreference can be used to avoid wrinkle formation during the bendingoperation, particularly on the concave portion of each bend in ahydroformed part. A suitable lubricant may be applied to the exterior ofthe blank 220 prior to placing it in the die assembly.

[0069] After bending, the tubular blank 220 is placed between the diehalves 228, 230 of a die assembly 232 and the assembly 232 is closed bybringing the two die halves 228, 230 together. The tubular blank 220 ispreferably immersed in a fluid bath so that it is filled withhydroforming fluid (not shown in the schematic representation of FIGS.11 and 12). A hydroforming ram assembly 234, 236 is engaged with eachend of the tubular blank 220 (see FIG. 12, for example) such that a rammember 238, 240 of each assembly 234, 236 seals a respective end of atubular blank 220. The ram members 238, 240 include hydraulicintensifiers which can intensify the hydroforming fluid, therebyincreasing the fluid pressure of the fluid within the blank 220 toirregularly outwardly expand (or deform) the tubular metallic wall 242of the tubular blank 220 into conformity with the die surfaces 244 ofthe die cavity (as disclosed, for example, in the '945 patent reference)to thereby form a hydroformed outer side rail member 32 having anexterior surface that is fixed into a predetermined irregularconfiguration.

[0070] The tubular blank 220 may have, for example, an essentially equaldiameter, essentially circular cross section along its length prior tooutward expansion during the hydroforming process. After hydroforming,the hydroformed member has a cross section that is determined by theshape of the die cavity. The shape of each die cavity used to form theouter side rail member 32 thus corresponds to the shape of the exteriorsurface of the member 32. Altering the cross-sectional configuration ofthe tubular hydroformed member 32 can be accomplished without departingfrom the principles of the present invention, however.

[0071] The hydroforming process may be computer controlled. The flow ofthe hydroforming fluid may be controlled to control, in turn, the mannerin which the metallic material of the blank 220 expands (in a radialdirection) during the hydroforming process. The ram members 314, 316 mayalso be controlled to push axially inwardly on opposite ends of theblank 220 during hydroforming to cause metal flow (in an axialdirection) within the blank 220 during outward expansion.

[0072] The fluid pressure and the axial pressure can be applied andcontrolled independently of one another. The ends of the tubular blank220 may be pushed axially inwardly during outward expansion to maintainthe wall thickness of the fully formed hydroformed member to within apredetermined range of the wall thickness of the initial tubular blank220. The ram members 238, 240 may be operated, for example, to maintainthe wall thickness of the outwardly expanding wall portions of the blank220 so that the wall thickness of the resulting hydroformed member iswithin about +/−10% of the original wall thickness of the blank 220(i.e., to compensate for wall thinning during diametric outwardexpansion of the tube).

[0073] If holes are to be formed in the member 32, the holes may beformed while the member 32 is in the die assembly 232 during thehydroforming operation or may be formed after the hydroformed member 32is removed from the die assembly along with any other required furtherprocessing of the member 32. Holes may be formed during the hydroformingprocess in a hydropiercing operation as disclosed, for example, in U.S.Pat. No. 5,460,026, which patent is hereby incorporated by reference inits entirety into the present application. Alternatively, holes (such asholes 70 and 72) or notches of various sizes and shapes may be cut(using a laser, for example) in the member 32 after the hydroformingoperation is completed and the hydroformed component is removed from thedie assembly 232.

[0074] As mentioned, openings 70, 72 are cut in the outer side railmembers 32, 34 to receive the B and C pillars. The openings 70 for the Bpillars are located in the example space frame 12 at the forwardmost endof the rear section 40 of each of the outer side rail members 32, 34.The B pillars are positioned to define the rearward extent of the dooropening 221. The openings 72 for the C pillars are at the rearwardmostend of the rearward section 40 of each of the outer side rail members32, 34. It can be understood from FIG. 1, for example, that the lengthof the rearward sections 40, 50 of the outer and inner side rail members32, 34 and 42, 44, respectively determine the distance between the B andC pillars and roughly determine the length of the rear compartmentportion (or sleeper compartment-defining portion) 152 of the cabassembly 10. Consequently, the size of the rearward compartment 10 canbe varied by varying the length of the rearward sections 40, 50 of theouter and inner side rail members 32, 34, 42, 44 and the length of therearward portions of the rail forming portions 192 of the upperlongitudinal members 162, 163. As mentioned, the rear compartmentportion 152 of the cab assembly 10 may be made long enough so that, forexample, a sleeper compartment is included in the rear portion of thecab assembly. Furthermore, because the length of the rear cab portion152 can vary between cab assemblies, the sleeper compartment of aparticular cab assembly may be constructed to be any one of a wide rangeof sizes.

[0075] Tubular hydroforming is particularly well suited for constructingcab assemblies having a wide range of sleeper compartment sizes becausea single die assembly can be constructed to enable the production ofhydroformed members having a wide range of lengths. More particularly,it can be understood from the discussion of the hydroforming processabove that each upper longitudinal member 162, 163, each inner side railmember 42, 44 and each outer side rail member 32, 34 is hydroformed in arespective die assembly. Each die assembly can be constructed to receiveblanks having a wide range of lengths so that a single set ofhydroforming die assemblies can be used to produce tubular hydroformingparts for constructing cab assemblies having a wide range of lengths.Thus, a single set of die assemblies can produce components for a widerange of cab assemblies, some having no sleeping compartments and othershaving sleeping compartments of a wide range of sizes. This concept canbe understood from, for example, an examination of FIGS. 11-13 whichillustrate the use of a single die assembly 232 to produce a relativelyshort outer side rail member 32 (FIGS. 11 and 12) and to produce arelatively long outer side rail member 250 (FIG. 13).

[0076]FIG. 11 shows the blank 220 within the die cavity 244 prior toexpansion. FIG. 12 shows the outer side rail member 32 that has beenformed from expansion of the blank 220 into conformity with the diecavity 244. Generally, the forward portion 222 of the blank 220 formsthe forward portion 36 of the rail member 32, the intermediate portion224 forms the intermediate portion 38 of the rail member 32 and therearward portion 226 forms the rearward section 40 of the rearwardmember 32. FIG. 13 shows the outer side rail member 250 after expansionof the blank from which it was formed (the blank for the member 250 isnot shown). It can be appreciated from a comparison of FIGS. 12 and 13that the forward portions 36 and 252 are of equal length to one anotherand that the intermediate portions 38 and 284 are of equal length to oneanother, but that the length of the rearward portion 256 of the outerside rail member 250 is longer than the length of the rearward section40 of the outer side remember 32. The blank (not shown, as mentioned)from which the outer side rail member 250 is made has forward andintermediate portions that are equal in length to the forward andintermediate portions 36, 38, respectively, of the blank 220 but has arearward portion that is longer than the length of the rearward section40 of the blank 220. Thus, the length of the rearward portion of aparticular blank used to form an outer side rail member corresponds(approximately) to the desired length of the steepercompartment-defining portion of the cab assembly being constructed.

[0077] The die cavity 244 of the die assembly 232 is shaped to receiveblanks of a wide range of lengths to produce rail members having a widerange of corresponding lengths. It can be appreciated that each of theinner side rail members and upper longitudinal members include arearward portion that defines a length that corresponds to the length ofthe sleeper compartment of the space frame constructed therefrom.Furthermore, the hydroforming tools 234, 236 are insertable into therespective ends of the die cavity 244 far enough to abut and seal therespective open tubular ends of the blank. Thus, the tool 236 can beinserted far enough to engage the rearward end of a blank regardless ofhow long the rearward portion thereof is.

[0078] It can also be understood that although the rearward sections 40of the outer side rail members 32, 34 (and the corresponding sections ofthe die cavity 244 of the die assembly 232) and the insertable portionsof the hydroforming tools to 34, 236 are essentially straight, this isnot required by the convention. The rearward section of the outer siderail members (and the inner side rail members can see rearward portionsof the rail forming portions of the upper longitudinal members) can bearcuate, for example, or some other non-straight shape. Similarly, theportions of the die cavity of the die assembly corresponding to thevariable length, non-straight portions and the associated insertableportions of the hydroforming tools can be non-straight as well.

[0079] The cab assembly 10 is mounted to the truck frame assembly 18 andmoved between its raised and operative positions in a conventionalmanner. The raising and lowering operation may be power operated ormanual. A pair of latch assemblies 282 (shown schematically in FIG. 10)are mounted on the truck frame assembly 18 and releasably engage thepair of latch engaging members 94 of the bracket assemblies 74, 75 ofthe cab assembly 10 to hold the cab assembly in its operative position.The two pairs of side rail members 32, 34 and 42, 44, the rear crossmember 52, the forward connecting structures 58, 60, and the rearU-shaped member 172 provide the cab assembly 10 with a high degree ofstructural strength which allows the cab assembly 10 to be pivoted toits raised position without deformation.

[0080] Other space frame embodiments are possible, however. For example,a space frame for a cab assembly could be constructed in which eachupper longitudinal member includes a pillar-forming portion that formsthe entire A pillar and an integral rail-forming portion. It iscontemplated, for example, when the entire a pillar and roof rail areprovided by a single hydroformed member, to form the upper longitudinalmember from a single integral blank or, alternatively, from a blank thatis comprised of two tubular metallic structures of different diameterthat are welded together end to end to form a blank which would then bebent (optionally) and hydroformed. To construct a blank from two tubularstructures of different diameter from one another, for example, and oneend of a small diameter blank could be expanded to have a diameter equalto the diameter of the larger diameter blank. The expanded end of thesmaller diameter tubular structure could then be butt welded to an endof the larger diameter tubular structure to form a two-piece blank thatis bent (optionally) and hydroformed to form an upper longitudinalmember.

[0081] It is also contemplated to provide a non-hydroformed structure(such as an assembly of stamped sheet metal parts) that forms the entireA pillar. The non-hydroformed A pillar could be connected to ahydroformed upper longitudinal member that provides a roof supportingrail on the associated side of the space frame.

[0082]FIG. 14 shows another example of the space frame 260 for a cabassembly 262. The cab assembly 262 is identical to the cab assembly 10except for the construction of the intermediate and rearward U-shapedassemblies 264, 266, thereof. Portions of the cab assembly 262 that areidentical to corresponding portions of the cab assembly 10 areidentified with identical reference numbers and are not separatelydiscussed.

[0083] Each U-shaped assembly 264, 266 of the cab assembly 262 is ofmulti-piece construction as opposed to the one-piece constructionillustrated in FIG. 1. Specifically, although any appropriate number ofelements can be employed, the assembly 264 includes three elements—apair of tubular hydroformed leg members 268, 270 and a tubularhydroformed cross member 272. Similarly the U-shaped member 266 includesa pair of tubular hydroformed leg members 274, 276 and a tubularhydroformed cross member 278. The leg members 268, 270 may be identicalto one another (so that they may be formed in the same hydroforming dieassembly) or they may be of mirror image construction to one another.Similarly the leg members 274, 276 of the U-shaped member 266 may beidentical to one another or may be of mirror image construction to oneanother. Each cross member 272, 278 is telescopically interengaged ateach end thereof with one leg member of the associated pair of legmembers and is secured thereto by welding at joints 279, 281,respectively.

[0084] It should be understood that each of the hydroformed members ofthe various space frames illustrated herein can be formed as a single,unitary member or as a multi-piece hydroformed member having multiplemembers that are attached to each other by welding or by otherappropriate fastening mechanisms.

[0085] The three piece construction of the assemblies 264, 266 allowsthe hydroformed portion of space frames to be easily and economicallyconstructed to provide cab assemblies having a wide range of widths.More specifically, a space frame can be made relatively wider by makingthe cross members 272, 278 relatively longer and a space frame can bemade relatively narrower by making the cross members 272, 278 relativelyshorter. It can be understood from FIG. 14 that the cross members 272,278 of each assembly 264, 266 constitute the bight portions of therespective U-shaped assemblies. Each cross member may be essentiallystraight or slightly arcuate. The length of the cross members 272, 278define the transverse distance between the B pillars and the C pillars,respectively, and consequently determined the width of the cab assembly.The cross member 52 can be constructed to have the length required tospan the distance between the rearward cans of the outer side railmembers 32, 34.

[0086] It can be appreciated from the discussion of the use of the dieassembly 232 to form outer side rail members of different lengths that asingle die assembly can be used to form cross members 272 or 278,respectively, having a wide range of lengths. It can also be appreciatedthat when the leg members 274, 276 or 268, 270 are of identicalconstruction to one another, the pairs of leg members 274, 276 or 268,270 can be formed in the same die assembly.

[0087] It should also be understood that in the description of theillustrated embodiment reference to welding to couple elements togetheris only one possible manner of coupling the elements together and thatother fastening mechanisms or fasteners can be used instead of ortogether with welding. Also, it should be understood that thenon-hydroformed members discussed herein can be formed of anynon-hydroforming process including stamping and other types ofprocesses. The references to “stamping” and to “stamped” sheet metalconstruction is made since it is a preferred method of manufacturing thenon-hydroformed members in the illustrated embodiment, however, othertypes of non-hydroforming processes can be employed in the illustratedembodiment.

[0088] It can be understood that, while illustrated embodiments of theinvention have been disclosed and described with reference with alimited number of embodiments, it will be apparent that variations andmodifications may be made thereto without departing from the spirit andscope of the invention. Therefore, the following claims are intended tocover such modifications, variations, and equivalents thereof inaccordance with the principles and advantages noted herein.

What is claimed is:
 1. A space frame for a truck cab, the space framecomprising: a pair of hydroformed, longitudinally extending inner siderail members; a laterally extending and hydroformed connecting memberextending between said inner side rail members and extending laterallybeyond each of said inner side rail members, said connecting memberbeing constructed and arranged to hold said pair of inner side railmembers in laterally spaced relation to one another; a U-shaped andhydroformed first upper cross member having a pair of leg portionsforming rear pillar structures and a transverse bight portion, each ofsaid rear pillar structures being connected to and extending upwardlyfrom said connecting member, and said pair of inner side rail membersbeing positioned between and spaced from said pair of leg portions; apair of hydroformed upper longitudinal members, each of said pair ofupper longitudinal members being coupled to said first upper crossmember; and a pair of hydroformed A-pillar members, each of said pair ofhydroformed A-pillar members being coupled to one of said pair of upperlongitudinal members, and wherein each of said pair of inner side railmembers, said connecting member, said first upper cross member, each ofsaid pair of upper longitudinal members, and each of said pair ofA-pillar members are continuous, tubular elements.
 2. A space frameaccording to claim 1, wherein each of said inner side rail members, saidconnecting member, and said first upper cross member are one-piece,tubular elements.
 3. A space frame according to claim 1, furthercomprising: a pair of hydroformed longitudinally extending outer siderail members; said connecting structure being constructed and arrangedto hold said pair of outer side rail members in laterally spacedrelation to one another; a pair of hydroformed upper longitudinalmembers each including a rail-forming portion, each of said rail-formingportions being coupled to an upper portion of one of said rear pillarstructures and extending forwardly from said respective rear pillarstructure; and a pair of forward pillar structures, each of said pair offorward pillar structures being connected at a lower end thereof to anassociated outer side rail member and being connected at an upper endthereof to an associated upper longitudinal member, said forward pillarstructures providing a pair of A pillars.
 4. A space frame according toclaim 1, wherein each of said outer side rail members includes a forwardsection at least a portion of which is constructed and arranged todefine a portion of a door opening of a cab portion.
 5. A space frameaccording to claim 3, further comprising: a pair of forward pillarassemblies of stamped sheet metal construction, each of said pair offorward pillar assemblies being connected to a respective outer siderail member and extending upwardly from said respective outer side railmembers, and each of said forward pillar assemblies being connected to arespective upper end to one of said pair of forward pillar structures.6. A space frame according to claim 3, wherein said A pillar defined byeach forward pillar assembly has a closed cross section.
 7. A spaceframe according to claim 3, wherein each of said pair of leg portionsextends downwardly from said bight portion at junctures at respectiveopposite ends of said bight portion, each of said junctures beingconnected to a rearward portion of a respective upper longitudinalmember such that each of said respective leg portions extends downwardlyfrom said respective upper longitudinal member and such that each ofsaid pair of leg portions is connected to a respective one of said outerside rail members to define said pair of rear pillar structures and suchthat said bight portion extends laterally between said upperlongitudinal members.
 8. A space frame according to claim 3, furthercomprising: a U-shaped and hydroformed second upper cross member havinga central bight portion and a pair of leg portions extending downwardlyfrom junctures at respective opposite ends of said bight portion, eachjuncture being connected to an intermediate portion of said respectiveupper longitudinal member such that each said leg portion extendsdownwardly from one of said upper longitudinal members and each of saidleg portions is connected to one of said outer side rail members todefine one of a pair of intermediate pillar structures and such thatsaid bight portion of said second cross member extends laterally betweensaid intermediate portions of said upper longitudinal members.
 9. Aspace frame according to claim 8, wherein said intermediate pillarstructures comprise the B pillars of said cab.
 10. A cab assemblyaccording to claim 8, wherein each of said first and second crossmembers is of three-piece construction.
 11. A space frame according toclaim 3, further comprising: forward laterally extending connectingstructures connecting forward end portions of each of said outer siderail members with a respective one of said inner side rail members. 12.A space frame according to claim 1, wherein said inner side rails, saidfirst cross member, and said laterally extending connecting structureare tubular.
 13. A space frame according to claim 1, wherein each ofsaid said inner side rails, said first cross member, and said laterallyextending connecting structure are hydroformed tubular member defined byan outwardly formed tubular, metallic wall fixed into a predeterminedexterior surface configuration corresponding to the respective diesurfaces in which said hydroformed tubular members were formed.
 14. Aspace frame for a motor vehicle, comprising: a main frame assembly; anda cab assembly pivotally coupled to said main frame assembly, said cabassembly having a pair of hydroformed, longitudinally extending innerside rail members; a laterally extending and hydroformed connectingmember extending between said inner side rail members and extendinglaterally beyond each of said inner side rail members, said connectingmember being constructed and arranged to hold said pair of inner siderail members in laterally spaced relation to one another; and a U-shapedand hydroformed first upper cross member having a pair of leg portionsforming rear pillar structures and a transverse bight portion, each ofsaid rear pillar structures being connected to and extending upwardlyfrom said connecting member, and said pair of inner side rail membersbeing positioned between and spaced from said pair of leg portions,wherein each of said pair of inner side rail members, said connectingmember, and said first upper cross member are continuous, tubularelements.
 15. A space frame according to claim 14, wherein each of saidinner side rails members includes a pivot member attached to a lowerside of said respective side rail member pivotally couple said cabassembly to said main frame assembly between and open position, in whichelements positioned below the cab assembly can be accessed and said siderail members and said connecting member are spaced from said main frameassembly, and a closed position in which said side rail members and saidconnecting member are substantially adjacent said main frame assembly.16. A space frame according to claim 14, wherein said inner side rails,said first cross member, and said laterally extending connectingstructure are one-piece, tubular elements.
 17. A method of forming aspace frame for a cab, comprising: forming each of a pair ofhydroformed, longitudinally extending inner side rails, a hydroformedconnecting member, a hydroformed first upper cross member, each of apair of hydroformed upper longitudinal members, and each of a pair ofhydroformed A-pillar members by a method comprising, providing a tubularmetallic blank having a tubular metallic wall; placing the tubularmetallic blank into a die cavity of a die assembly, the die cavityhaving die surfaces, and providing a high pressure fluid into aninterior of the blank to expand the metallic wall of the central portionof the blank outwardly into conformity with the surfaces of the diecavity to define the respective hydroformed member; mounting theconnecting member to each of the inner side rails; mounting the firstupper cross member to said connecting member; mounting each of the upperlongitudinal members to the first upper cross member; and mounting eachof the A-pillar members to one of the upper longitudinal members.
 18. Amethod according to claim 17, further comprising: forming outer siderail members by a method comprising, providing a tubular metallic blankhaving a tubular metallic wall; placing the tubular metallic blank intoa die cavity of a die assembly, the die cavity having die surfaces, andproviding a high pressure fluid into an interior of the blank to expandthe metallic wall of the central portion of the blank outwardly intoconformity with the surfaces of the die cavity to define the respectivehydroformed member; and wherein the mounting of the first upper crossmember to the connecting member includes mounting the outer side railsto the connecting member.